To this point in the chapter, we have focused upon the attraction that occurs between people who are initially getting to know one another. But the basic principles of social psychology can also be applied to help us understand relationships that last longer.
When good friendships develop, when people get married and plan to spend the rest of their lives together, and when families grow closer over time, the relationships take on new dimensions and must be understood in somewhat different ways. Yet the principles of social psychology can still be applied to help us understand what makes these relationships last.
The factors that keep people liking and loving each other in long-term relationships are at least in part the same as the factors that lead to initial attraction. For instance, regardless of how long they have been together, people remain interested in the physical attractiveness of their partners, although it is relatively less important than for initial encounters.
And similarity remains essential. Relationships are also more satisfactory and more likely to continue when the individuals develop and maintain similar interests and continue to share their important values and beliefs over time (Davis & Rusbult, 2001).
Both actual and assumed similarity between partners tend to grow in long-term relationships and are related to satisfaction in opposite-sex marriages (Schul & Vinokur, 2000). Some aspects of similarity, including that in terms of positive and negative affectivity,
have also been linked to relationship satisfaction in same-sex marriages (Todosijevic, Rothblum, & Solomon, 2005). However, some demographic factors like education and income similarity seem to relate less to satisfaction in same-sex partnerships than they do in opposite sex ones (Todosijevic, Rothblum, & Solomon, 2005).
